This is very worrying and why is this required? We do not know anything about the site like who runs it or the security setup. Therefore, fear my personal information from PayPal would be at risk if you wanted to sell, use to to try and impersonate me or your database gets hacked. Lastly, it's just plain bad business that you are planning on terminating accounts of paid in full good customers over this.

Your paypal email is just an email address without the password.
Nobody is asking you about your password anywhere.

If you click the button, you will see that you are taken to the official PayPal website (click the site info in your browser to see the original PayPal certificates) and you are not on our website anymore and you will see what information the PayPal API sends us.
Exactly 3 things: Your email address, your "locale" (country code) and if your account is verified by PayPal, so WE know, that you are not a cheater and a scammer.
Because the coin has always two sides :-P

The paypal login is like the Facebook login on other sites.

It's way more secure to log in with paypal, than with us.

We have different reasons why we had to integrate it, but the main reason was security.

If you pay, we have your paypal email address anyway. If I wanted to sell your email address, I could do it anyway and I would have done it a long a time ago.